The 1946 Vancouver Island earthquake (M = 7.2) triggered a rock avalanche from the north face of Mount Colonel Foster, central Vancouver Island, British Columbia. Approximately 1.5 × 10 6 m 3 of Triassic volcaniclastic rocks detached from between el. 1965 m and el. 1600 m. Although just over half of this volume was deposited in the upper part of the track above el. 1080 m, approximately 0.7 × 10 6 m 3 descended the lower part of the track and entered the waters of Landslide Lake at el. 890 m. The resultant displacement wave ran up a maximum vertical distance of 51 m on the opposite shore and the wave crest was about 29 m high when it spilled over the lip of the lake. Water displaced during the event destroyed forest in the upper reaches of the Elk River valley up to 3 km from Landslide Lake. The wave at Landslide Lake is comparable to other waves generated by similar magnitude rock avalanches in Peru and Norway and it is the largest recorded in the Canadian Cordillera. The case history illustrates the conditions where substantial damage may be caused by a rock avalanche well beyond the limits of its debris when it produces a landslide-generated wave in the mountainous terrain of the Cordillera.
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Stephen G. Evans (1989) studied this question.